In a vote freighted with geopolitical implications, Crimeans went to the polls Sunday in a snap referendum on whether to break away from Ukraine and join Russia, the former ruler of this Black Sea peninsula.

While Crimean Tatars and ethnic Ukrainians boycotted the hastily organized vote, pro-Russian voters compared it to a homecoming guaranteeing a brighter future.

“I was born in Crimea in 1950, when it was Russia, and now I’m voting to go back to my homeland,” said Aleksander Kromel after casting a ballot at a polling station in Simferopol, the regional capital. “I’m voting for the power of the Russian state to finally bring us out of this mess that the Ukrainians have made of us. We’ve been on our knees for 20 years living under the Ukrainians.”

Russia’s red, blue and white flag adorned windows and balconies of apartment houses across the regional capital, including a large one draped in front of the regional parliament. Russian Cossacks guarded the building’s entrances, part of a huge Russian security presence here that critics say is a form of intimidation.

Sunday’s referendum asks whether Crimea should be annexed by Russia or revert to a 1992 Ukrainian constitution under which Crimea can set its own foreign policy. Kiev considers the referendum illegitimate; the US and the European Union have said they will not recognize the results.

Just four hours after polls opened, the pro-Russian regional prime minister, Sergei Aksyonov, announced that voter turnout was already 50 percent. Official results of the referendum will be announced Monday. But the outcome of the referendum seems to be a foregone conclusion given the ethnic-Russian majority among the peninsula’s 2 million population. For them, joining Moscow means escaping the yoke of a Western Ukrainian government now in power in Kiev.

“We’ve always wanted to rejoin Russia,” said Aleksander Leonov, a polling station supervisor. “But this wave of support for the referendum rose up when the bandits took power in Kiev.”

Last month’s ousting of former President Viktor Yanukovych amid mass protests has brought to power an interim cabinet made up of former opposition members. In Crimea, as in other parts of Ukraine’s Russian-oriented east and south, the new leaders in Kiev are accused of trying to impose an unfriendly, Western Ukrainian agenda.

“We’re just too different from the Western Ukrainians. We can’t live as one nation with them any more,” Mr. Kromel, a retiree, said. “We’re are simple, open-hearted Slavic people who believe in the Orthodox church. The Western Ukrainians are Catholic and more materialistic.”

Tartar boycott

The referendum does not allow voters to keep Crimea’s current status as an autonomous region of Ukraine. Crimean Tatars boycotted the vote, saying it was illegal. The Tatars are a Turkic ethnic group who are Muslims, and represent about 12 percent of the peninsula’s population. In 1944, Soviet rulers expelled around 200,000 Tartars to central Asia; the survivors and their descendants were only allowed to return in the 1980s.

At the polling station in the Cultural Center of Simferopol’s Kamenka district, a majority Tatar neighborhood, less than 10 percent of the almost 1,800 registered voters had shown up by 1 p.m., according to a supervisor.

Across the street from the dilapidated, Soviet-era building, several Tatar men stood by and watched as a few voters trickled in.

“This referendum is a bad joke,” said Ayder Abibialayev, who abstained from voting. “You can’t hold a referendum in 15 days. This was organized by the Kremlin, and they’re having us vote with a gun to our head.”

Ukraine’s Interior Ministry estimates that there are about 20,000 Russian soldiers occupying Crimea. Russian President Vladimir Putin claims they are local self-defense teams there to protect Ukraine’s threatened Russian-speakers.

“Ukraine is now teaching Russia a lesson about how to get rid of dictators,” said Timor Teifukov, a Tatar who boycotted the referendum. “Putin is afraid of what Ukraine is now showing Russia, that’s why he’s manufactured this referendum.”